OSTEOBLASTIC CELLS FROM RAT LONG BONE II: ADHESION TO SUBSTRATA AND INTEGRIN EXPRESSION IN PRIMARY AND PROPAGATED CULTURES

Propagation in vitro of rat tibial osteoblasts (ROB) is accompanied by increased expression of the early osteogenic marker alkaline phosphatase (AP) and maturation of the osteogenic phenotype. In order to establish the pattern of the integrin expressed in ROB during progression to the mature osteoblastic phenotype, we have used biosynthetic, immunoblotting and immuno-histochemical assays. We immunoprecipitated from osteoblasts, expanded for 1.5- and 7.5-doubling, α5β1, αvβ3, α3β1, α6β1 and α1β1 integrin heterodimers; furthermore β5, α2 and α4 chains were detected by immunoblots and indirect immunofluorescence. αv, α1, α6 subunits in most cells, and β3 and β1 subunits in a minority, were found to be associated with adhesion plaques in osteoblasts of 1.5-, 4.5- and 7.5-doubling grown in the presence of FCS, while all other subunits stained diffusely all the cells. Adhesion to fibronectin (FN), laminin (LN), collagen type I (COL I) and III (COL III) by ROB at different doubling (1.5–11) was dependent on substratum concentration, and after 2.5h at 55nm 60% of the cells adhered to all substrata. Arg-Gly-Asp-Ser (RGDS) containing peptides inhibited adhesion of cells differentially, according to substratum; no dependence on extent of progation in vitro was observed. In conclusion, ROB cultured in vitro for 1.5- to 11-doubling had an unchanged pattern of expression of integrin subunits, heterodimer association and cellular distribution. Adhesion specificity and affinity were also unchanged. These results suggest that the phenotypic maturation, detected as an increase in AP expression, is not accompanied by major changes in the potential for cell—matrix interactions, and does not correspond to changes in the type of integrin subunits expressed by osteoblasts.     

Ultrastructural Aspects of the Nectary Spur of Limodorum abortivum (L) Sw. (Orchidaceae)

The ultrastructure of the nectary spur of Limodorum abortivum(L) Sw. was examined before and after anthesis. In cross sectionthe nectary spur shows an internal epidermal layer of thin-walledcells bordering the secretory cavity and 10–12 layersof parenchyma cells. The ultrastructure of the secretory cellssuggests the involvement of ER, Golgi and plastids in nectarsecretion. The nectar accumulated in the sub-cuticular spaceis released into the nectariferous cavity by rupture of theouter layer of the cuticle. Limodorum abortivum (L) Sw., Orchidaceae, nectary spur, nectar secretion, ultrastructure, anthesis, endoplasmic reticulum, dictyosomes, plastids     

Genome-wide Analysis of Transcript Abundance and Translation in Arabidopsis Seedlings Subjected to Oxygen Deprivation

Annals of Botany 96: 647–660, 2005 Unfortunately, there were errors in Figure 5 of this article.The     

Specific and Common Epitopes in Mating Pheromones of Euplotes raikovi Revealed by Monoclonal Antibodies

Polypeptide mating pheromones Er-1 and Er-2, purified from the supernatant of Euplotes raikovi cultures of mating type I and mating type II, respectively, were used to immunize mice and obtain monoclonal antibodies. Five hybridoma clones producing antibodies specific to the mating pheromones were selected. They were analyzed for immunospecificity by immunoperoxidase assay, immunoblotting, and for their efficacy in inhibition of mating pheromone activity. Monoclonal antibodies from two hybridoma clones recognized only the mating pheromone used as antigen; those from the other three clones reacted, to comparable extents, with both mating pheromones. On the basis of these results it was assumed that two immunogenic sites exist in Er-1 and Er-2, one specific and the other common to both mating pheromones.     

Morphometric and advertisement call geographic variation in polyploid green toads

We describe the spatial pattern of variation of morphometric characters and call acoustic properties of tetraploid green toads [Bufo viridis complex) from eight populations in Central Asia, and we analyse the causal agents responsible for the patterns observed, by means of partial Mantel tests. Populations significantly differ with respect to both body size and body shape. Since animals inhabiting the driest regions are smaller, but not younger, man animals from less dry areas, we suggest that their small body size is due to the limiting effect of arid climate on growth rate. Differences in body shape are positively associated only with geographic distances, and we suggest that isolation by distance might have played an important role in determining the pattern of variation. Populations significantly differ also with respect to the acoustic properties of the call, in particular, with respect to temperature-adjusted pulse rate and body size-adjusted fundamental frequency; that is, with respect to those properties which are under the strongest morphological or physiological constraints, and that show the lowest variability within individuals (static properties). The pattern of variation of calls shows positive association with geographic distances, but not with climatic distances. Calls do vary, and in this region the main causal agent responsible for call variation might have been the isolation by distance. The evolutionary implications of these results are discussed.     

Diagnosing and assessing uncertainties of terrestrial ecosystem models in a multimodel ensemble experiment: 1. Primary production

We conducted an ensemble modeling exercise using the Terrestrial Observation and Prediction System (TOPS) to evaluate sources of uncertainty in carbon flux estimates resulting from structural differences among ecosystem models. The experiment ran public‐domain versions of biome‐bgc, lpj, casa , and tops‐bgc over North America at 8 km resolution and for the period of 1982–2006. We developed the Hierarchical Framework for Diagnosing Ecosystem Models (HFDEM) to separate the simulated biogeochemistry into a cascade of three functional tiers and sequentially examine their characteristics in climate (temperature–precipitation) and other spaces. Analysis of the simulated annual gross primary production (GPP) in the climate domain indicates a general agreement among the models, all showing optimal GPP in regions where the relationship between annual average temperature (T, °C) and annual total precipitation (P, mm) is defined by P=50T+500. However, differences in simulated GPP are identified in magnitudes and distribution patterns. For forests, the GPP gradient along P=50T+500 ranges from ～50 g C yr^?1 m^?2 °C^?1 (casa ) to ～125 g C yr^?1 m^?2 °C^?1 (biome‐bgc ) in cold/temperate regions; for nonforests, the diversity among GPP distributions is even larger. Positive linear relationships are found between annual GPP and annual mean leaf area index (LAI) in all models. For biome‐bgc and lpj , such relationships lead to a positive feedback from LAI growth to GPP enhancement. Different approaches to constrain this feedback lead to different sensitivity of the models to disturbances such as fire, which contribute significantly to the diversity in GPP stated above. The ratios between independently simulated NPP and GPP are close to 50% on average; however, their distribution patterns vary significantly between models, reflecting the difficulties in estimating autotrophic respiration across various climate regimes. Although these results are drawn from our experiments with the tested model versions, the developed methodology has potential for other model exercises.     

Temperature and development rate of Triatoma guasayana (Hemiptera: Reduviidae) eggs under laboratory conditions: physiological and adaptive aspects

Abstract.  Eggs laid in the laboratory by T. guasayana (Wygodzinsky & Abalos 1949) adults collected from wild biotopes in Santiago del Estero (Argentina) were exposed to fluctuating temperatures, and 172 egg batches, involving 1574 eggs, completed development. Their development times were fitted to the linear degree-day model and three nonlinear models ( devar , Lactin, and Rueda). Parameter values and 95% CL were estimated. The lower development threshold is estimated to be 15 °C (linear devar model) and 17.5 °C (Lactin model), and the temperature resulting in the shortest development time is estimated to be between 26 °C (Lactin model) and 37 °C (nonlinear devar model). The thermal death point by the Lactin model is 34.4 °C, and conforms well with other studies. Differences between the present results and those of other studies for T. guasayana are discussed in terms of the maternal effects, the influence of experimental conditions, and the rate summation effect. Using the climatic conditions of the natural environment of T. guasayana , the results are interpreted in terms of physiological adaptation. A generalized development rate response of T. guasayana eggs to increasing temperature is proposed, with three ranges: between 10 and 14.8 °C development rate increases in an accelerating way; between 14.8 and 29.2 °C development rate increases more or less linearly, and between 29.2 and 34 °C development rate decreases.     

Nutrient content affecting Spodoptera frugiperda and Dalbulus maidis occurrence in corn

This work aims to study the effect of the nutrient contents in the leaves of corn on the incidence of Spodopterafrugiperda （Smith） （Lepidoptera： Noctuidae） and Dalbulus maidis （Delong ＆ Wolcott） （Homoptera： Cicadellidae）. The treatments were represented by unfertilized corn plants and corn plants fertilized with 250 kg of the formulation 4-14-8 （N- P-K） ＋ 100 kg of ammonium sulfate （AS）/ha and 500 kg of the formulation 4-14-8 （N-P-K） ＋200 kg of AS/ha, arranged in randomized blocks with four replicates. Attacks by S. frugiperda and D. maidis were higher as the nitrogen, sulfur, calcium and copper content in the leaves of corn increased. The effects of calcium and copper found in this study were not consistent with that of lower susceptibility associated with higher levels of these nutrients mentioned in the literature. We believe that there was a cumulative effect of the nutrients altogether, building up a nutritiously better vegetable which in turn had less reserve for defense, or that the content of both nutrients in the leaves were not high enough to induce such effects.